For 30 minutes, spacewalking astronauts were on their own after a storm cut off the radio link between them and NASA commanders on the ground, Reuters reported.

That left spacewalkers Danny Olivas and Nicole Stott to complete their mission while being supervised by their colleagues inside the international space station. The blackout occurred after the astronauts had already disconnected an ammonia tank, the main task of the 6.5 hour walk. On Thursday, astronauts will install a replacement tank of coolant, according to Reuters.

Last weekend, space shuttle Discovery arrived at the space station to delivery supplies and a treadmill bearing comedian Stephen Colbert's name. The shuttle is set to return to Earth on September 10.